Fmrp and cancer treatment

ABSTRACT

The present invention provides compositions and methods for down-modulating the expression and/or the immuno-suppressive activity of i) the FMRP protein, ii) an mRNA encoding the FMRP protein, and/or iii) the FMR1 gene for the treatment and/or prevention of primary cancer and/or cancer metastasis in a subject in need thereof.

RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No. 16/867,763, filed May 6, 2020, which claims the benefit of EP patent application serial number 19172927.6, filed on May 7, 2019, the contents of which are incorporated herein by reference in its entirety.

SEQUENCE LISTING

The sequence listing submitted via EFS, in compliance with 37 CFR § 1.52(e)(5), is incorporated herein by reference. The sequence listing XML file submitted via EFS contains the file 43033000 US1 Seq List.xml, created on Oct. 26, 2022, which is 56,780 bytes in size.

FIELD OF THE INVENTION

The present invention provides compositions and methods for modulating the expression and/or activity of i) the FMRP protein (hereinafter “FMRP”), ii) an mRNA encoding the FMRP and/or iii) the FMR1 gene that encodes FMRP for the treatment and/or prevention of cancer and/or cancer metastasis in a subject in need thereof.

BACKGROUND OF THE INVENTION

The discovery of immune checkpoint receptors and the development of checkpoint blockade-based immunotherapy is one of the most notable successes in basic research and clinical treatment for cancer, for it raised the possibility to cure some malignant tumors¹. Immunomodulatory agents targeting T cell co-inhibitory immune checkpoints such as the programmed death-1 (PD-1) or its ligand (PD-L1), the cytotoxic T-lymphocyte antigen 4 (CTLA-4) have been approved for the treatment of different types of malignant tumors¹.

However, across the spectrum of human cancer types, a widely variable proportion (40-90%) of patients with different forms of cancer have little or no benefit from the well-known PD-1 or CTLA-4 blockade-based immunotherapy², notably including those with pancreatic ductal adenocarcinoma (PDAC)^(3,4). Thus, additional immunotherapeutic strategies are still urgently needed.

SUMMARY OF THE INVENTION

The present invention provides an agent capable of down-modulating the expression and/or the immuno-suppressive activity of i) the FMRP protein, ii) an mRNA encoding the FMRP protein, and/or iii) the FMR1 gene that encodes FMRP for use in the treatment and/or prevention of primary cancer and/or cancer metastasis in a subject in need thereof.

Also provided is a plasmid or a vector comprising one or more nucleic acid(s) encoding the miRNA, siRNA, piRNA, hnRNA, snRNA, esiRNA, shRNA, and/or antisense oligonucleotide of the invention.

Further provided is a host cell comprising a plasmid or vector of the invention or one or more nucleic acid(s) encoding the miRNA, siRNA, piRNA, hnRNA, snRNA, esiRNA, shRNA, and/or antisense oligonucleotide of the invention.

Also provided is a plasmid or a vector comprising one or more nucleic acid(s) encoding the peptide or analog thereof, an antibody or an antigen-binding fragment of said antibody, or antibody mimetic of the invention.

Further provided is a host cell comprising a plasmid or vector of the invention or one or more nucleic acid(s) encoding the peptide or analog thereof, an antibody or an antigen-binding fragment of said antibody, or antibody mimetic of the invention.

Further provided is a pharmaceutical composition comprising:

i) a therapeutically effective amount of an agent capable of modulating the expression and/or activity of the FMRP protein, an mRNA encoding the FMRP and/or the FMR1 gene, or

ii) a plasmid or a vector of the invention, or

iii) a host cell of the invention, and a pharmaceutically acceptable carrier or diluent.

Further provided is a pharmaceutical composition that targets FMRP for selective and efficient degradation comprising an agent as disclosed herein, wherein such agent is chemically linked to an E3-ubiquitin ligase. The agent binds tightly to the FMRP to form an FMRP-agent complex while the E3-ubiquitin ligase that directs the bound protein to the proteasome for degradation.

Also provided is a method of treatment and/or prevention of cancer and/or cancer metastasis in a subject in need thereof, comprising administering to said subject an agent of the invention.

Also provided is a method of treatment and/or prevention of cancer and/or cancer metastasis in a subject in need thereof, comprising administering to said subject a pharmaceutical composition of the invention.

Without wishing to be bound to any particular theory, it is believed that engineered upregulation in cells or tissues of the FMR1 gene (endogenous or via gene therapy) to produce FMRP protein at similar levels as in many tumors, or delivery of FMRP protein or FMR1 mRNA, could be a strategy to ameliorate autoimmune diseases such as Type 1 diabetes, et al, where there is chronic or otherwise inappropriate infiltration of CD8 (cytotoxic) T cells with pathological effects. Similarly, the success of cell therapies involving transplantation of stem and other cells could be enhanced if such cells were engineered to over-express FMRP, either stably (via lentivirus transduction or CRISPR/Cas9 genome editing), or transiently via AAV.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A-1J. Deletion of FMRP in mouse PDAC cancer cells strikingly prolongs overall survival and severely impairs tumor growth and metastasis in immunocompetent but not immuno-deficient mice. (A) Representative images and quantification of FMRP expression in mouse normal pancreas, premalignant PanIN lesions, and PDAC tumor tissues of P48-cre; LSL-KrasG12D; P53R172H/+ PDAC mouse model in the FVBN background. n=3 mice per group. Student T-test was used. Scale bar, 100 μm. Immunostaining of human PDAC tissue-microarrays (not shown) corroborates the results in mouse PDAC. (B) Expression of FMRP in a ‘wild-type (WT)’ mouse PDAC cell line (4361.12) and its absence in derivative FMRP deficient cells (‘KO’), which are generated by transiently transfection of Cas9/SgRNA vectors targeting the mouse FMR1 gene that encodes FMRP, as revealed by western blotting using two different FMRP antibodies that recognize different epitopes of the FMRP protein (Abcam, ab191411; Cell signaling, 4317s). Three independent experiments. (C) Colony formation of 4361.12 WT2 and FMRP KO2 cells in culture. Indicated number of cancer cells were seeded into one well of a six-well plate. Ten days later, the cells were fixed and stained by crystal violet. Three independent experiments; (D) Schematic of the in vivo lung metastasis assay. In brief, 2X10{circumflex over ( )}5 cells were injected into the tail vein of immunocompetent FVBN or immunodeficient SCID/Beige mice, which seeds cancer cells in the lung. Mice were monitored twice per week, and were sarcrified when reaching a veterniary endpoint. (E-F) Overall survival of syngeneic immunocompetent FVBn or immunodeficient SCID/Beige mice injected with murine PDAC WT2 or FMRP KO2 cells, n=5 mice per group, Kaplan-Meier test was used. (G) Expression of FMRP in mouse PDAC cell line 4361.12 WT cells and its absence in a second FMRP KO cell line (KO8), also generated by transiently transfection with Cas9/SgRNA vectors targeting the mouse FMR1 gene, as revealed by western blotting. Three independent experiments. (H) Schematic of the in vivo subcutaneous (s.c.) primary tumor growth model. In brief, 5X10{circumflex over ( )}5 cells were s.c. injected under the skin of FVBN or NSG mice. Tumor-bearing mice were monitored twice per week, and sarcrified at day 25 after the injection, when WT tumor volume reaches 1000 mm{circumflex over ( )}3. (I-J) Tumor weight from FVBn (I) or immunodeficient NSG (J) mice injected with murine PDAC WT (2 independent clones WT2 and WT3) or FMRP KO (2 independent clones KO2 and KO8) cells at day 28, n=4˜10 mice per group, the unpaired T-test was used.

FIG. 2A-2H. Deletion of FMRP in mouse PDAC cancer cells elicits an intense anti-tumor immune response in the form of infiltrating CD8+ (cytotoxic) T lymphocytes. (A) Immunochemical staining and quantification of CD8+ (cytotoxic) T lymphocytes in primary tumors formed by mouse PDAC WT and KO cells, scale bar, 100 μm, n=3 mice for each group; (B) IF staining and quantification of CD45+ immune cells in primary tumors formed by mouse PDAC WT2 and KO2 cells, scale bar, 100 μm, n=3 mice for each group; (C-G) FACS analysis was used to determine the frequency of CD45+ immune cells, of CD3+CD8+ T cells, and of activated GRZb+, IFNγ+ and TNFα+, CD8 T cells, in PDAC WT and FMRP KO tumors growing in immunocompetent mice. n=4˜5 mice per group, two independent experiments. The unpaired T-test was used. (H) Representative double immunostaining images of FMRP and CD8 expression in the center and in the edge of mouse PDAC tissues from P48-cre; LSL-KrasG12D; P53R172H/+ PDAC mouse model in the FVBN background. n=8 mouse PDAC samples. Paired T-test was used. Scale bar, 100 μm. The data support the interpretation that FMRP is preventing the influx of CD8 T cells that is seen in the KO tumors (Panel A). Immunostaining of human PDAC tissue-microarrays for CD8 and FMRP (not shown) shows an inverse correlation between density of infiltrating CD8 T cells and expression of FMRP, concordant with the results in mouse PDAC.

FIG. 3A-3D. The FMRP KO in cancer cells sensitizes otherwise resistant PDAC tumors to immunotherapy involving anti-PD1 antibody treatment. (A,B) FMRP deletion does not suppress PD-L1 expression in mouse PDAC cells in vitro or in vivo. (A) WB analysis of PD-L1 expression in mouse PDAC WT and FMRP KO cells, three independent experiments. (B) Immunostaining to detect PD-L1 expression in tumors formed by murine PDAC WT and FMRP KO cells, scale bar, 100 μm, n=3 mice for each group. (C, D) PDAC WT2 and KO2 tumor growth curves without or with anti-PD-1 antibody therapy (I.P., 200 ug per mice, twice per week), all in FVBn mice. n=7˜11 mice per group, the unpaired T-test was used. (C) This result indicates that PDAC tumors arsising from this mouse PDAC cancer cell line are insensitive to anti-PD-1 treatment. (D) In notable contrast, the FMRP KO severely impairs PDAC tumor growth associated with an increased influx of CD8 T cells (as show in FIGS. 1G-I, 2A, and 4D), suggesting that FMRP inhibitors could have therapeutic efficacy in tumors resistant to anti-PD1/PD-L1 therapies.

FIG. 4A-4D. Combined deletion of the genes encoding FMRP and the RNA A to I editing protein ADAR1 in mouse PDAC further prolongs survival. (A) FMRP and ADAR1 interact in PDAC cancer cells, as determined by co-immunoprecipitation experiments in mouse PDAC 4361.12 WT2 cells. FMRP and ADAR1 were visualized in a western blot on total cell lysate prior to and after immunoprecipitation with rabbit anti FMRP antibody (Abcam, ab191411). Normal rIgG antibody was used as control. Three independents experiments. (B) The FMRP-ADAR1 interaction was also verified by a reverse co-immunoprecipitation experiment, wherein FMRP and ADAR1 were revealed by immunostaining western blots of total cell lysate prior to and after immunoprecipitation with mouse anti ADAR1 antibody (Santa Cruz, sc73408). Normal mIgG antibody was used as control. Three independents experiments. (C) Western blotting validation of FMRP and ADAR1 expression in WT2, FMRP KO, ADAR1 KO, and FMRP/ADAR1 double KO cells, which were generated by transient transfection with Cas9/SgRNA vectors targeting the mouse FMRJ and ADAR1 genes. Three independents experiments. (D) Overall survival of FVBn mice injected with WT2, FMRP KO, ADAR1 KO, and FMRP/ADAR1 double KO cells; the Kaplan-Meier test was used. In brief, 5X10{circumflex over ( )}5 cells were s.c. injected into the flanks of FVBN mice. The mice were monitored twice per week, and sarcrified when tumor volumes reached 1000 mm{circumflex over ( )}3.

FIG. 5A-5I. Deletion of FMRP in cancer cells of a second tumor type, colon cancer, similarly impairs tumor growth in immunocompetent but not immunodeficient mice. (A) Representative images of immunohistochemistry staining and quantification of FMRP expression in mouse normal colon and adenomas tissues of AKP (ApcΔ/Δ; Kras^(G12D/+); Trp53Δ/Δ; CDX2 Cre ERT2) or APC (ApcΔ/Δ; CDX2 Cre ERT2) mouse model. n=3 mice for each group. Student T-test was used. Scale bar, 100 μm. Immunostaining of human colon cancer tissue-microarrays (not shown) corroborates the mouse data. (B) Western blotting validation of FMRP expression in CT26 WT and FMRP KO subclones that were generated by transient transfection with Cas9/SgRNA vectors targeting the mouse FMR1 gene. The deletion of FMRP in CT26 cells were verified by two independent antibodies (Abcam, ab191411; Cell Signaling Technology, CST, #4317), which recognize different epitopes of FMRP protein. Three independents experiments. (C) Colony formation assay of CT26 WT17 # and KO12 #cells. 1250 cancer cells were seeded in one well of a six-well plate. 10 days later, cells were fixed and stained using crystal violet; three independents experiments. (D) Schematic of the in vivo subcutaneous (s.c.) primary tumor growth model. In brief, 5X10{circumflex over ( )}5 cells were injected s.c. into immunocompetent Balb/c or immunodeficient NSG mice. Mice were monitored twice per week, and sarcrified day 25 or 18 after the injection, when WT tumor volumes reached 1000 mm{circumflex over ( )}3. (E) Tumor growth curlve of Balb/c mice injected with CT26 WT17 # or FMRP KO12 #cells until day 25 after s.c. injection, n=10 mice per group, the unpaired T-test was used. (F) Representative images and tumor weight from Balb/c mice injected with CT26 WT17 # or FMRP KO12 #cells at day 25, n=10 mice per group, the unpaired T-test was used. (G) Immunochemical staining of CD8 and FMRP in primary tumors formed by CT26 WT17 # or FMRP KO12 #cells, scale bar, 100 μm, n=3 mice for each group (left panel); Quantification of CD8+ T cells in primary tumors formed by CT26 WT17 # or FMRP KO12 #cells (right panel); n=3 mice for each group. Student T-test was used. Scale bar, 100 μm. (H) Tumor growth curve of NSG mice injected with CT26 WT12 # or FMRP KO12 #cells until day 14 after s.c. injection, n=5 mice per group, the unpaired T-test was used. (I) Representative images and tumor weight from NSG mice injected with CT26 WT17 # or FMRP KO12 #cells at day 14, n=5 mice per group, the unpaired T-test was used.

FIG. 6A-6E. Deletion of FMRP in mouse melanoma cells significantly impairs tumor growth in immunocompetent mice. (A) Representative images of immunohistochemistry staining and quantification of FMRP expression in mouse normal skin and melanoma tissues of the iBIP2 (inducible BRAF INK/ARF PTEN) melanoma mouse model in the FVBN background. n=2 mice for normal skin group and 4 mice for the iBIP2 melanoma group. Student T-test was used. Scale bar, 100 μm. (B) Western blotting validation of FMRP expression in B16-OVA WT and FMRP KO subclones that were generated by transient transfection with Cas9/SgRNA vectors targeting the mouse FMRJ gene. Three independents experiments. (C) Colony formation assay of B16-OVA WT and FMRP KO cells. 1250 cancer cells were seeded in one well of a six-well plate. 10 days later, cells were fixed and stained using crystal violet; three independents experiments. (D) Tumor growth curlve of C57B/6 mice injected with B16-OVA WT or FMRP KO cells until day 18 after s.c. injection, n=5-10 mice per group, the unpaired T-test was used. In brief, 5X10{circumflex over ( )}5 cells were s.c. injected into the flanks of C57B/6 mice. Mice were monitored twice per week, and sarcrified on day 18 after the injection, when WT tumor volume reached 1000 mm{circumflex over ( )}3. (E) Representative images and tumor weight from immunocompetent mice injected with B16-OVA WT or FMRP KO cells, collected at day 18, n=5-10 mice per group; the unpaired T-test was used.

FIGS. 7A and 7B. Specific deletion of FMRP in incipient cancer cells in the genetically engineered RIP1-Tag2 (RT2) mouse model of multistep pancreatic neuroendocrine tumorigenesis (PanNET) significantly prolongs survival. (A) Representative images of immunohistochemical staining of FMRP expression in mouse normal pancreas, PanNET tumors and liver metastasis; n=3 mice for each group. Scale bar, 100 μm. (B) Overall survival of male RT2 and FMRP KO RT2 mice, Kaplan-Meier test was used. Male FMRP KO RT2 mice, in which the FMR1 gene encoding FMRP was specially deleted in the pancreric islet β cells cells that express the oncogene SV40 driving PanNET tumorigenesis, were generated by crossing FMR1 floxed mice with Rip1-Tag2 (RT2) and RIP7-Cre mice; n=17 for the FMRP KO RT2 group, and n=12 for the RT2 group. All the mice were monitored twice per week, and were sacrified upon reacing a veterinary endpoint.

FIGS. 8A and 8B. Elevated FMRP expression in mouse breast cancer tissues. (A) Representative images and quantification of FMRP expression in mouse normal mammary fat pat (MFP) and de novo breast tumors of the genetically engineered MMTV-PymT breast cancer mouse model. n=3 mice per group. Student T-test was used. Scale bar, 100 μm. (B) Representative images and quantification of FMRP expression in mouse normal mammary fat pat (MFP) and de novo breast tumors of the genetically engineered C3Tag triple-negative breast cancer (TNBC) mouse model. n=3 mice for normal MFP group and 3 mice for C3Tag breast cancer group. Student T-test was used. Scale bar, 100 μm. Immunostaining of human triple negative breast cancer (TNBC) tissue-microarrays (not shown) corroborates the results in mouse breast cancer.

FIG. 9A-9C. Inhibition of FMRP in mouse PDAC cells via siRNAs. (A) Migration assay of mouse PDAC 4361.12 WT2 cells and FMRP KO2 cells. In brief, 5000 cells in 50 μl of serum-free DMEM medium were seeded in the top well of a Boyden chamber (pore size of the membrane, 8 μm), 200 μl DMEM medium with FBS were placed in the bottom chamber. 18 hours later, cancer cells remaining in the well were removed using cotton swabs with 70% EtOH. Those cells that migrated through the membrane via the 8-μm pores were fixed, and then stained with crystal violet. The number of migrated cells were counted. Data were collected from 3 independent wells. the unpaired T-test was used. Three independents experiments. (B) Western blotting validation of FMRP expression in mouse PDAC 4361.12 WT2 cells transfected with control siRNA (i.e., siCtrl: UAAGG CUAUG AAGAG AUAC (SEQ ID NO: 9)), and siRNAs targeting FMRP (siFMRP #1: AUAAG AGACA ACUUG GUGC (SEQ ID NO: 10); and siFMRP #2: UAACUUCGGAAUUAUGUAG (SEQ ID NO: 11)). Three independents experiments. (C) Migration assay of mouse PDAC 4361.12 WT2 cells transfected with control siRNA, and siRNAs targeting FMRP; 5000 cells per well for 18 hr. Data were collected from 3 independent wells. the unpaired T-test was used. Three independents experiments.

FIGS. 10A and 10B. FRET-based high-though screen (HTS) for FMRP inhibitors A. Schematic of FRET-based high-though screen (HTS) for FMRP inhibitors. Human FMRP protein is produced in human HEK 293 cells, purified, and biochemically labeled with the fluorescent reporter fluorescein. 2) The sc1 RNA1 is labeled with a fluorescence quencher molecule, either Cy3 or BHQ, such that when sc1 is bound to FMRP, the excitable fluorescence emission of FITC is quenched. 3) Compounds that elicit the release of the quenched fluorescence are subjected to further characterization to validate their capability to disrupt the interaction of FMRP and sc1. B. Mammalian expressed FMRP-His protein purification profile. Human FMRP protein is produced in human HEK 293 cells, purified and validated. Left panel, Coomassie blue staining showing 2 ug total protein in each lane. Right panel, Western blot of FMRP-His protein expression by using anti-His Tag antibody. M. Molecular weight marker. Me. Culture medium. FT. Flow through. W. Washes. E. Eluted fractions. Eluted fractions were pooled, buffer exchanged and concentrated.

FIG. 11 demonstrates the widespread and highly prevalent expression of FMRP across the spectrum of human cancer types (reproduced from The Human Protein Atlas; proteinatlas.org/ENSG00000102081-FMR1/pathology).

DESCRIPTION OF THE INVENTION

Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. The publications and applications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. In addition, the materials, methods, and examples are illustrative only and are not intended to be limiting.

In the case of conflict, the present specification, including definitions, will control. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in art to which the subject matter herein belongs. As used herein, the following definitions are supplied in order to facilitate the understanding of the present invention.

The term “comprise/comprising” is generally used in the sense of include/including, that is to say permitting the presence of one or more features or components.

As used in the specification and claims, the singular form “a”, “an” and “the” include plural references unless the context clearly dictates otherwise.

As used herein, “at least one” means “one or more”, “two or more”, “three or more”, etc.

As used herein the terms “subject”/“subject in need thereof”, or “patient”/“patient in need thereof” are well-recognized in the art, and, are used interchangeably herein to refer to a mammal, including dog, cat, rat, mouse, monkey, cow, horse, goat, sheep, pig, camel, and, most preferably, a human. In some cases, the subject is a subject in need of treatment or a subject with a disease or disorder. However, in other aspects, the subject can be a normal subject. The term does not denote a particular age or sex. Thus, adult and newborn subjects, whether male or female, are intended to be covered. Preferably, the subject is a human. Most preferably a human suffering from of cancer and/or cancer metastasis or a human that might be at risk of suffering from cancer and/or cancer metastasis.

The terms “nucleic acid”, “polynucleotide,” and “oligonucleotide” are used interchangeably and refer to any kind of deoxyribonucleotide (e.g. DNA, cDNA, . . . ) or ribonucleotide (e.g. RNA, mRNA, . . . ) polymer or a combination of deoxyribonucleotide and ribonucleotide (e.g. DNA/RNA) polymer, in linear or circular conformation, and in either single —or double—stranded form. These terms are not to be construed as limiting with respect to the length of a polymer and can encompass known analogues of natural nucleotides, as well as nucleotides that are modified in the base, sugar and/or phosphate moieties (e.g. phosphorothioate backbones). In general, an analogue of a particular nucleotide has the same base-pairing specificity, i.e., an analogue of A will base-pair with T.

The term “vector”, as used herein, refers to a viral vector or to a nucleic acid (DNA or RNA) molecule such as a plasmid or other vehicle, which contains one or more heterologous nucleic acid sequence(s) of the invention and, preferably, is designed for transfer between different host cells. The terms “expression vector”, “gene delivery vector” and “gene therapy vector” refer to any vector that is effective to incorporate and express one or more nucleic acid(s) of the invention, in a cell, preferably under the regulation of a promoter. A cloning or expression vector may comprise additional elements, for example, regulatory and/or post-transcriptional regulatory elements in addition to a promoter.

The term “about,” particularly in reference to a given quantity, is meant to encompass deviations of plus or minus ten (10) percent.

While focusing on the role of FMRP in promoting the invasive growth of pancreatic neuroendocrime and ductal cancers, the Inventors surprisingly discovered the unexpected and unprecedented role of FMRP in suppressing anti-tumor immunity in vivo.

The fragile X mental retardation protein (FMRP), an RNA-binding protein that is highly expressed in the brain, binds to a subset of specific mRNAs of synaptic (and other) proteins and regulates their translation in neurons⁶. Due to the critical role of FMRP in synaptic function, the lack of its expression leads to the fragile X syndrome (FXS), the most common form of inherited intellectual disabilities and one main cause of autism⁷. Different from this role, other studies of FMRP have revealed it to be expressed in several types of cancer^(8,9), and have implicated it in cancer cell survival, invasion, and metastasis. The term FMRP also refers to FMRP isoforms in the present disclosure.

The inventors have shown that the absence of the FMRP expression in mouse pancreatic ductal adenocarcinoma cells (PDAC) and colon carcinoma cells strikingly prolongs overall survival and severely impairs tumor growth in syngeneic immunocompetent mice.

The present invention thus provides an agent capable of modulating the expression and/or activity of i) the FMRP protein, ii) an mRNA encoding the FMRP and/or iii) the FMR1 gene for use in the treatment and/or prevention of cancer and/or cancer metastasis in a subject in need thereof.

Preferably, the modulation of the expression and/or activity of the FMRP protein includes the regulatory interactions of the FMRP protein with its mRNA and miRNA targets (through, e.g., its RNA-binding domains), and/or with other proteins.

In certain embodiments, the modulation is a reduction in FMRP mRNA level. In certain embodiments, the modulation is a reduction in FMRP protein level and/or activity. In certain embodiments, both FMRP mRNA and protein levels are reduced. Such reduction may occur in a time-dependent or in a dose-dependent manner.

As used herein, “inhibition” or “reduction” are used interchangeably to mean a reduction of target nucleic acid levels or target protein levels in the presence of an agent of the invention compared to target nucleic acid levels or target protein levels in the absence of the agent of the invention.

In one aspect, the agent of the invention inhibits the translation of an RNA encoding FMRP.

In another aspect, the agent of the invention inhibits the transcription of a DNA encoding FMRP.

In a further aspect, the agent inhibits or impairs the binding of the FMRP to a target mRNA, and/or the agent inhibits or impairs the binding of FMRP to its interacting proteins or other molecules via which it transmits its immune-suppressive activity.

Preferably, the cancer and/or cancer metastasis to be treated is resistant to immunotherapy and is selected from the non-limiting examples of cancers including carcinoma, blastoma, sarcoma, melanoma, lymphoma, and leukemia or lymphoid malignancies. More particular examples of such cancers include breast cancer, colon cancer, rectal cancer, colorectal cancer, kidney or renal cancer, clear cell cancer lung cancer including small-cell lung cancer, non-small cell lung cancer, adenocarcinoma of the lung and squamous carcinoma of the lung, squamous cell cancer (e.g. epithelial squamous cell cancer), cervical cancer, ovarian cancer, prostate cancer, prostatic neoplasms, liver cancer, bladder cancer, cancer of the peritoneum, hepatocellular cancer, gastric or stomach cancer including gastrointestinal cancer, gastrointestinal stromal tumor, pancreatic cancer, head and neck cancer, glioblastoma, retinoblastoma, astrocytoma, thecomas, arrhenoblastomas, hepatoma, hematologic malignancies including non-Hodgkins lymphoma (NHL), multiple myeloma, myelodysplasia disorders, myeloproliferative disorders, chronic myelogenous leukemia, and acute hematologic malignancies, endometrial or uterine carcinoma, endometriosis, endometrial stromal sarcoma, fibrosarcomas, choriocarcinoma, salivary gland carcinoma, vulval cancer, thyroid cancer, esophageal carcinomas, hepatic carcinoma, anal carcinoma, penile carcinoma, nasopharyngeal carcinoma, laryngeal carcinomas, Kaposi's sarcoma, mast cell sarcoma, ovarian sarcoma, uterine sarcoma, melanoma, malignant mesothelioma, skin carcinomas, Schwannoma, oligodendroglioma, neuroblastomas, neuroectodermal tumor, rhabdomyosarcoma, osteogenic sarcoma, leiomyosarcomas, Ewing Sarcoma, peripheral primitive neuroectodermal tumor, urinary tract carcinomas, thyroid carcinomas, Wilm's tumor, as well as abnormal vascular proliferation associated with phakomatoses, edema (such as that associated with brain tumors), and Meigs' syndrome.

Usually, the agent of the invention is a chemical compound, a peptide or analog thereof, a nucleic acid, an antibody, an antigen-binding fragment of said antibody or antibody mimetic. Preferably, the agent is able to access the intracellular compartments of cancer cells, given the predominant subcellular localization of FMRP in the cytoplasm.

As used herein, a “chemical agent or compound” is a compound that produces change by virtue of its chemical composition and its effects on living tissues and organisms. The chemical agent may be a small molecule inhibitor (SMI), a nucleic acid—e.g. a siRNA—or a peptide. In embodiments, the chemical compound is preferably a non-peptidyl molecule. Most preferably, the non-peptidyl molecule is inducing selective intracellular proteolysis of a peptide encoded by a nucleic acid sequence of the invention. Examples of chemical compounds inducing selective intracellular proteolysis comprise proteolysis targeting chimera (PROTAC) protein degraders and small-molecule chemical modulators of deubiquitinating enzymes upstream of or on the proteasome. As known in the art, PROTACs, also known as Active Degraders, are heterobifunctional small molecules composed of two active domains and a linker capable of removing specific unwanted proteins.

Compositions of matter that inhibit FMRP and thus recapitulate the invention revealed by gene knockout can be discovered and validated using a number of techniques and methodologies known to those of skill in the art. The following are illustrative of the spectrum of approaches that can be used to identify FMRP inhibitors with potential for therapeutic development of anti-cancer drugs.

In case the agent is a peptide, then it will preferably be conjugated to an agent that increases the accumulation of the peptide in the cancer cell. Such an agent can be a compound which induces receptor mediated endocytosis such as for example the membrane transferrin receptor mediated endocytosis of transferrin conjugated to therapeutic drugs (Qian Z. M. et al., “Targeted drug delivery via the transferrin receptor-mediated endocytosis pathway” Pharmacological Reviews, 54, 561, 2002) or a cell membrane permeable carrier which can, be selected e.g. among the group of fatty acids such as decanoic acid, myristic acid and stearic acid, which have already been used for intracellular delivery of peptide inhibitors of protein kinase C (Ioannides C. G. et al., “Inhibition of IL-2 receptor induction and IL-2 production in the human leukemic cell line Jurkat by a novel peptide inhibitor of protein kinase C” Cell Immunol., 131, 242, 1990) and protein-tyrosine phosphatase (Kole H. K. et al., “A peptide-based protein-tyrosine phosphatase inhibitor specifically enhances insulin receptor function in intact cells” J. Biol. Chem. 271, 14302, 1996) or among peptides. Preferably, cell membrane permeable carriers are used. More preferably a cell membrane permeable carrier peptide is used.

In case the cell membrane permeable carrier is a peptide then it will preferably be a positively charged amino acid rich peptide.

Preferably such positively charged amino acid rich peptide is an arginine rich peptide. It has been shown in Futaki et al. (Futaki S. et al., “Arginine-rich peptides. An abundant source of membrane-permeable peptides having potential as carriers for intracellular protein delivery” J. Biol. Chem., 276, 5836, 2001), that the number of arginine residues in a cell membrane permeable carrier peptide has a significant influence on the method of internalization and that there seems to be an optimal number of arginine residues for the internalization, preferably they contain more than 6 arginines, more preferably they contain 9 arginines (R9).

The peptide may be conjugated to the cell membrane permeable carrier by a spacer (e.g. two glycine residues). Any cell membrane permeable carrier can be used as determined by the skilled artisan. In this case, the cell membrane permeable carrier is preferably a peptide.

Usually arginine rich peptides are selected from the non-limiting group comprising the HIV-TAT 48-57 peptide (GRKKRRQRRR; SEQ ID NO. 14), the FHV-coat 35-49 peptide (RRRRNRTRRNRRRVR; SEQ ID NO. 15), the HTLV-II Rex 4-16 peptide (TRRQRTRRARRNR; SEQ ID NO. 16) and the BMV gag 7-25 peptide (KMTRAQRRAAARRNRWTARXSEQ ID NO. 17).

Since an inherent problem with native peptides (in L-form) is degradation by natural proteases, the peptide, as well as the cell membrane permeable peptide, of the invention may be prepared to include D-forms and/or “retro-inverso isomers” of the peptide. In this case, retro-inverso isomers of fragments and variants of the peptide, as well as of the cell membrane permeable peptide, of the invention are prepared.

In case the agent is a nucleic acid, then it is selected from the group comprising a nucleic acid encoding an miRNA, an siRNA, a piRNA, an hnRNA, an snRNA, an sg RNA, an esiRNA, an shRNA, and an antisense oligonucleotide (e.g. modified ASO), or a combination thereof.

When the agent is a nucleic acid, the agent can be prepared by any suitable art recognized method such as phosphoramidite or H-phosphonate chemistry, which can be carried out manually or by an automated synthesizer. The nucleic acid based agents of the invention may also be modified in a number of ways without compromising their ability to hybridize to their target (see e.g., Agrawal and Gait, Advances in Nucleic Acid Therapeutics, (2019) doi.org/10.1039/9781788015714).

In embodiments wherein the agent is an miRNA, siRNA, piRNA, hnRNA, snRNA, sgRNA, esiRNA, shRNA, or antisense compound the agent is targeted to a human FMRP nucleic acid. Nucleotide sequences that encode human FMRP include, without limitation, the following: GENBANK Accession No. NM_001185075.1 (incorporated herein as SEQ ID NO: 1); GENBANK Accession No. NM_001185076.1 (incorporated herein as SEQ ID NO: 2), GENBANK Accession No. NM_001185081.2_(incorporated herein as SEQ ID NO: 3); GENBANK Accession No. NM_001185082.2_(incorporated herein as SEQ ID NO: 4); and GENBANK Accession No. NM_002024.6_(incorporated herein as SEQ ID NO: 5).

Nucleotide sequences that encode murine (mouse) FMRP include, without limitation, the following: GENBANK Accession No. NM_001290424.1 (incorporated herein as SEQ ID NO: 6); GENBANK Accession No. NM_001374719.1 (incorporated herein as SEQ ID NO: 7), and GENBANK Accession No. NM_008031.3_(incorporated herein as SEQ ID NO: 8).

The terms “microRNA,” “miRNA,” and “MiR” are interchangeable and refer to endogenous or artificial non-coding RNAs that are capable of regulating gene expression. It is believed that miRNAs function via RNA interference. The design of such microRNAs is within the skill of ordinary artisans.

The terms “siRNA” and “short interfering RNA” are interchangeable and refer to single-stranded or double-stranded RNA molecules that are capable of inducing RNA interference. siRNA molecules typically have a duplex region that is between 18 and 30 base pairs in length. The design of such siRNAs is within the skill of ordinary artisans.

The terms “piRNA” and “Piwi-interacting RNA” are interchangeable and refer to a class of small RNAs involved in gene silencing. PiRNA molecules typically are between 26 and 31 nucleotides in length. The design of such PiRNAs is within the skill of ordinary artisans. Examples of modified antisense oligonucleotides (ASOs) include the GapmeRs. As used herein, a GapmeR is a chimeric antisense oligonucleotide that contains a central block of deoxynucleotide monomers sufficiently long to induce RNase H cleavage. Usually, the GapmeRs of the invention are directed against one or more mRNA encoding the FMRP or a target mRNA. The design of such GapmeRs is within the skill of ordinary artisans.

The terms “sgRNA” and “guideRNA” are interchangeable and refer to a specific RNA sequence that recognizes the target DNA region of interest and directs the endonuclease there for editing. The gRNA is usually made up of two parts: crispr RNA (crRNA), a 17-20 nucleotide sequence complementary to the target DNA, and a tracr RNA, which serves as a binding scaffold for the Cas nuclease.

Any suitable engineered sgRNA, or crRNA and tracrRNA, can be employed as long as it is effective for recognizing a target DNA of the invention. The design of such sgRNA, or crRNA and tracrRNA is within the skill of ordinary artisans. The sgRNA can, e.g., be directed to recognize the FMR1 DNA, for example, an sgRNA selected from the group comprising 5′-GTGGAAGTGCGGGGCTCCAA-3′ (SEQ ID NO: 12) and 5′-GAGCTGGTGGTGGAAGTGCG-3 (SEQ ID NO: 13), or a combination thereof.

The terms “snRNA” and “small nuclear RNA” are interchangeable and refer to a class of small RNAs involved in a variety of processes including RNA splicing and regulation of transcription factors. The subclass of small nucleolar RNAs (snoRNAs) is also included. The term is also intended to include artificial snRNAs, such as antisense derivatives of snRNAs. The design of such snRNA is within the skill of ordinary artisans.

In particular, the invention therefore provides isolated siRNA comprising short double-stranded RNA from about 18 to about 30 nucleotides in length, that are targeted to the mRNA encoding the FMRP or the target mRNA. The term “isolated” means altered or removed from the natural state through human intervention. For example, an siRNA naturally present in a living animal is not “isolated,” but a synthetic siRNA, or an siRNA partially or completely separated from the coexisting materials of its natural state is “isolated.” An isolated siRNA can exist in substantially purified form, or can exist in a non-native environment such as, for example, a cell into which the siRNA has been delivered. The siRNAs of the invention can comprise partially purified RNA, substantially pure RNA, synthetic RNA, or recombinantly produced RNA, as well as altered RNA that differs from naturally occurring RNA by the addition, deletion, substitution and/or alteration of one or more nucleotides. Such alterations can include addition of non-nucleotide material, such as to the end(s) of the siRNA or to one or more internal nucleotides of the siRNA, including modifications that make the siRNA resistant to nuclease digestion.

One or both strands of the siRNA of the invention can also comprise a 3′ overhang. A “3′ overhang” refers to at least one unpaired nucleotide extending from the 3′-end of an RNA strand. Thus, in one aspect, the siRNA of the invention comprises at least one 3′ overhang of from one to about six nucleotides (which includes ribonucleotides or deoxynucleotides) in length, preferably from one to about five nucleotides in length, more preferably from one to about four nucleotides in length, and particularly preferably from about one to about two nucleotides in length.

In the case both strands of the siRNA molecule comprise a 3′ overhang, the length of the overhangs can be the same or different for each strand. In a most preferred embodiment, the 3′ overhang is present on both strands of the siRNA and is two nucleotides in length. In order to enhance the stability of the present siRNAs, the 3′ overhangs can also be stabilized against degradation. In one embodiment, the overhangs are stabilized by including purine nucleotides, such as adenosine or guanosine nucleotides.

Alternatively, substitution of pyrimidine nucleotides by modified analogues, e.g., substitution of uridine nucleotides in the 3′ overhangs with 2′-deoxythymidine, is tolerated and does not affect the efficiency of RNAi degradation. In particular, the absence of a 2′ hydroxyl in the 2′-deoxythymidine significantly enhances the nuclease resistance of the 3′ overhang in tissue culture medium.

The siRNAs of the invention can be targeted to any stretch of approximately 18-30, preferably 19-25 contiguous nucleotides in any of the target mRNA sequences (including the mRNA encoding the FMRP). Techniques for selecting target sequences for siRNA are well known in the art. Thus, the sense strand of the present siRNA comprises a nucleotide sequence identical to any contiguous stretch of about 18 to about 30 nucleotides in the target mRNA.

The siRNAs of the invention can be obtained using a number of techniques known to those of skill in the art. For example, the siRNAs can be chemically synthesized or recombinantly produced using methods known in the art. Preferably, the siRNA of the invention are chemically synthesized using appropriately protected ribonucleoside phosphoramidites and a conventional DNA/RNA synthesizer. The siRNA can be synthesized as two separate, complementary RNA molecules, or as a single RNA molecule with two complementary regions. Commercial suppliers of synthetic RNA molecules or synthesis reagents include Proligo (Hamburg, Germany), Dharmacon Research (Lafayette, Colo., USA), Pierce Chemical (part of Perbio Science, Rockford, Ill., USA), Glen Research (Sterling, Va., USA), ChemGenes (Ashland, Mass., USA), Qiagen (Hilden, Germany) and Cruachem (Glasgow, UK).

Alternatively, siRNA can also be expressed from recombinant circular or linear DNA plasmids using any suitable promoter. Suitable promoters for expressing siRNA of the invention from a plasmid include, for example, the U6 or H1 RNA pol III promoter sequences and the cytomegalovirus promoter. Selection of other suitable promoters is within the skill in the art. The recombinant plasmids of the invention can also comprise inducible or regulatable promoters for expression of the siRNA in a particular tissue or in a particular intracellular environment. The siRNA expressed from recombinant plasmids either can be isolated from cultured cell expression systems by standard techniques or can be expressed intracellularly in neurons.

The siRNAs of the invention can also be expressed from recombinant viral vectors intracellularly in neurons. The recombinant viral vectors comprise sequences encoding the siRNAs of the invention and any suitable promoter for expressing the siRNA sequences. Suitable promoters include, for example, the U6 or H1 RNA pol III promoter sequences and the cytomegalovirus promoter. Selection of other suitable promoters is within the skill in the art. The recombinant viral vectors of the invention can also comprise inducible or regulatable promoters for expression of the siRNA in the brain (e.g., in hippocampal neurons), in the prostate, etc . . . .

In one embodiment, the one or more siRNA of the invention is selected from the non-limiting group comprising siRNA targeting human FMRP (S5317, S5316) from Thermo Scientific.

In one embodiment, the one or more siRNA of the invention is selected from the non-limiting group consisting of siFMRP #1: AUAAG AGACA ACUUG GUGC (SEQ ID NO: 10); and siFMRP #2: UAACUUCGGAAUUAUGUAG (SEQ ID NO: 11).

The agent of the invention may also be selected from an antibody, an antigen-binding fragment of said antibody, or an antibody mimetic. Preferably, when the agent is an antibody, an antigen-binding fragment of said antibody, or an antibody mimetic, it is in the form of a plasmid or a vector comprising one or more nucleic acid(s) encoding the antibody, antigen-binding fragment of said antibody, or antibody mimetic, such that it can be delivered inside the cancer cell, where FMRP is localized in the cytoplasm and the nucleus.

As used herein, an “antibody” is a protein molecule that reacts with a specific antigenic determinant or epitope and belongs to one or five distinct classes based on structural properties: IgA, IgD, IgE, IgG and IgM. The antibody may be a polyclonal (e.g. a polyclonal serum) or a monoclonal antibody, including but not limited to fully assembled antibody, single chain antibody, antibody fragment, and chimeric antibody, humanized antibody as long as these molecules are still biologically active and still bind to at least one peptide of the invention. Preferably the antibody is a monoclonal antibody. Preferably also the monoclonal antibody will be selected from the group comprising the IgG1, IgG2, IgG2a, IgG2b, IgG3 and IgG4 or a combination thereof. Most preferably, the monoclonal antibody is selected from the group comprising the IgG1, IgG2, IgG2a, and IgG2b, or a combination thereof.

A typical antibody is composed of two immunoglobulin (Ig) heavy chains and two Ig light chains. Several different types of heavy chain exist that define the class or isotype of an antibody. These heavy chain types vary between different animals. All heavy chains contain a series of immunoglobulin domains, usually with one variable (VH) domain that is important for binding antigen and several constant (CH) domains. Each light chain is composed of two tandem immunoglobulin domains: one constant (CL) domain and one variable domain (VL) that is important for antigen binding.

For the production of antibodies, various host animals may be immunized by injection with the FMRP gene product, or a portion thereof including, but not limited to, portions of the FMRP gene product in a recombinant protein. Such host animals may include but are not limited to rabbits, mice, and rats, to name but a few. Various adjuvants may be used to increase the immunological response, depending on the host species, including but not limited to Freund's (complete and incomplete), mineral gels such as aluminum hydroxide, surface active substances such as lysolecithin, pluronic polyols, polyanions, peptides, oil emulsions, keyhole limpet hemocyanin, dinitrophenol, and potentially useful human adjuvants such as BCG (bacille Calmette-Guerin) and Corynebacterium parvum.

Monoclonal antibodies may be prepared by using any technique which provides for the production of antibody molecules by continuous cell lines in culture. These include but are not limited to the hybridoma technique originally described by Kohler and Milstein, 1975, Nature, 256:495-497, the human B-cell hybridoma technique (Kosbor et al., 1983, Immunology Today, 4:72, Cote et al., 1983, Proc. Natl. Acad. Sci., 80:2026-2030) and the EBV-hybridoma technique (Cole et al., 1985, Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, Inc., pp. 77-96). In addition, techniques developed for the production of “chimeric antibodies” (Morrison et al., 1984, Proc. Natl. Acad. Sci., 81:6851-6855; Neuberger et al., 1984, Nature, 312:604-608; Takeda et al., 1985, Nature, 314:452-454) by splicing the genes from a mouse antibody molecule of appropriate antigen specificity together with genes from a human antibody molecule of appropriate biological activity can be used. Alternatively, techniques described for the production of single chain antibodies (U.S. Pat. No. 4,946,778) can be adapted to produce single chain antibodies specific to one of the binding partners.

The term “isolated”, when used as a modifier of an antibody of the invention means that the antibody is made by the hand of man or is separated, completely or at least in part, from their naturally occurring in vivo environment. Generally, isolated antibodies are substantially free of one or more materials with which they normally associate with in nature, for example, one or more protein. The term “isolated” does not exclude alternative physical forms of the antibodies, such as multimers/oligomers, modifications (e.g., phosphorylation, glycosylation, lipidation) or derivatized forms, or forms expressed in host cells produced by the hand of man.

An “isolated” antibody can also be “substantially pure” or “purified” when free of most or all of the materials with which it typically associates with in nature. Thus, an isolated antibody that also is substantially pure or purified does not include polypeptides or polynucleotides present among millions of other sequences, such as antibodies of an antibody library or nucleic acids in a genomic or cDNA library.

Antibody fragments which recognize specific epitopes may be generated by known techniques. An “antigen binding fragment” comprises a portion of a full-length antibody. Examples of antigen binding fragments include Fab, Fab′, F(ab′)2, and Fv fragments; diabodies; minobodies; nanobodies; linear antibodies (Zapata et al. (1995) Protein Eng. 8(10):1057-1062); single-chain antibody molecules; and multispecific antibodies formed from antibody fragments.

Such fragments can be produced by pepsin digestion of the antibody molecule and the Fab fragments which can be generated by reducing the disulfide bridges of the F(ab′)2 fragments. Alternatively, Fab expression libraries may be constructed (Huse et al., 1989, Science, 246:1275-1281) to allow rapid and easy identification of monoclonal Fab fragments with the desired specificity.

Preferably, the antibody or an antigen-binding fragment of said antibody is either engineered so that it penetrates into cells or is directly expressed within cells using a gene therapy style approach. These latter are intracellular antibodies, which may also be called intrabodies, that are produced in the cell, and bind an antigen (e.g. FMRP protein, an mRNA encoding the FMR, etc. . . . ) within the same cell.

The present invention also contemplates a gene delivery vector, preferably in the form of a plasmid or a vector, that comprises one or more nucleic acid(s) encoding the miRNA, siRNA, piRNA, hnRNA, snRNA, sgRNA, esiRNA, shRNA, the peptide or analog thereof, the antibody or antigen-binding fragment of said antibody, or a similar intracellular antibody mimetic, and/or antisense oligonucleotide of the invention. As used herein, a “vector” is capable of transferring nucleic acid sequences to target cells (e.g., viral vectors, non-viral vectors, particulate carriers, and liposomes).

Suitable vectors include derivatives of SV40 and known bacterial plasmids, e.g., E. coli plasmids col E1, pCR1, pBR322, pMB9 and their derivatives, plasmids such as RP4; phage DNAs, e.g., the numerous derivatives of phage X, e.g., NM989, and other phage DNA, e.g., Ml 3 and filamentous single stranded phage DNA; yeast plasmids such as the 2p plasmid or derivatives thereof, vectors useful in eukaryotic cells, such as vectors useful in insect or mammalian cells; vectors derived from combinations of plasmids and phage DNAs, such as plasmids that have been modified to employ phage DNA or other expression control sequences; and the like.

Various viral vectors are used for delivering nucleic acid to cells in vitro or in vivo. Non-limiting examples are vectors based on Herpes Viruses, Pox-viruses, Adeno-associated virus, Lentivirus, and others. In principle, all of them are suited to deliver the expression cassette comprising an expressible nucleic acid molecule that codes for an miRNA, a siRNA, a piRNA, a hnRNA, a snRNA, an sgRNA, a esiRNA, a shRNA, and an antisense oligonucleotide of the invention.

Alternatively, the gene delivery vector of the invention, preferably the viral vector is issued for delivering a CRISPR-based loss-of-function system comprising i) at least one sgRNA, or crRNA and tracrRNA, targeting a regulatory sequence of FMR1 gene or a genomic DNA sequence encoding the FMRP mRNA, and ii) and a structure-guided endonuclease such as an RNA-guided endonuclease. Any suitable naturally occurring, or engineered, RNA-guided endonuclease can be employed as long as it is effective for specifically binding a target DNA of the invention and it may be selected from the non-limiting group comprising Cas9, Cpf1, and FEN-1. Preferably, the RNA-guided endonuclease is Cas9.

In a preferred aspect, said viral vector is an adenoviral vector, preferably a lenti- or baculo- or most preferably adeno-viral/adeno-associated viral (AAV) vectors but other means of delivery or vehicles are known (such as yeast systems, microvesicles, gene guns/means of attaching vectors to gold nanoparticles) and are provided, in some aspects, one or more of the viral or plasmid vectors may be delivered via liposomes, nanoparticles, exosomes, microvesicles, or a gene-gun. More preferably, the viral vector is selected from the group comprising an adeno-associated virus (AAV) and a lentivirus. Lentivirus of 1st, 2nd, and 3rd generation.

Also contemplated in the present invention is a host cell comprising a plasmid or vector of the invention or one or more nucleic acid(s) encoding the miRNA, siRNA, piRNA, hnRNA, snRNA, sgRNA, esiRNA, shRNA, a CRISPR-based loss-of-function system and/or antisense oligonucleotide of the invention. The host cell can be any prokaryotic or eukaryotic cell, preferably the host cell is a eukaryotic cell, most preferably the host cell is a mammalian cell. The host cell of the invention can deliver the plasmid or vector of the invention to the cancer cell(s) using a number of techniques known to those of skill in the art, such as e.g. exosomes and microvesicles.

Also provides herein is a pharmaceutical composition comprising:

-   -   i) a therapeutically effective amount of an agent modulating the         expression and/or activity of the FMRP protein, an mRNA encoding         the FMRP and/or the FMR1 gene as described herein, or     -   ii) a plasmid or a vector of the invention, or iii) a host cell         of the invention, and a pharmaceutically acceptable carrier or         diluent.

The pharmaceutical compositions of the present invention may be manufactured in a manner that is itself known, e.g., by means of conventional mixing, dissolving, granulating, dragee-making, levigating, emulsifying, encapsulating, entrapping or lyophilizing processes. Proper formulation is dependent upon the route of administration chosen. Techniques for formulation and administration of the compounds of the instant application may be found in “Remington's Pharmaceutical Sciences,” Mack Publishing Co., Easton, Pa., latest edition.

Any agent of the invention can be administered to an animal, including a human patient, by itself, or in pharmaceutical compositions where it is mixed with suitable carriers or excipient(s) at doses therapeutically effective to treat or ameliorate a variety of disorders, including those characterized by insufficient, aberrant, or excessive FMRP activity.

In some embodiments, the pharmaceutical composition of the invention is useful in the treatment and/or prevention of cancer and/or cancer metastasis in a subject in need thereof.

The term “therapeutically effective amount” as used herein means an amount of an agent modulating the expression and/or activity of the FMRP protein, an mRNA encoding the FMRP and/or the FMR1 gene high enough to significantly positively modify the symptoms and/or condition to be treated, but low enough to avoid serious side effects (at a reasonable risk/benefit ratio), within the scope of sound medical judgment.

The therapeutically effective amount of the agent modulating the expression and/or activity of the FMRP protein, an mRNA encoding the FMRP and/or the FMR1 gene is selected in accordance with a variety of factors including type, species, age, weight, sex and medical condition of the patient; the severity of the condition to be treated; the route of administration; the renal and hepatic function of the patient. A physician of ordinary skill in the art can readily determine and prescribe the effective amount of the drug required to prevent, counter or arrest the progress of cancer and/or cancer metastasis.

“Pharmaceutically acceptable carrier or diluent” means a carrier or diluent that is useful in preparing a pharmaceutical composition that is generally safe, non-toxic, and desirable, and includes carriers or diluents that are acceptable for human pharmaceutical use.

Such pharmaceutically acceptable carriers can be sterile liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. Water is a preferred carrier when the pharmaceutical composition is administered intravenously. Saline solutions and aqueous dextrose and glycerol solutions can also be employed as liquid carriers, particularly for injectable solutions.

Pharmaceutically acceptable excipients include starch, glucose, lactose, sucrose, sodium stearate, glycerol monostearate, talc, sodium chloride, dried skim milk, glycerol, propylene glycol, water, ethanol and the like.

The pharmaceutical compositions may further contain one or more pharmaceutically acceptable salts such as, for example, a mineral acid salt such as a hydrochloride, a hydrobromide, a phosphate, a sulfate, etc.; and the salts of organic acids such as acetates, propionates, malonates, benzoates, etc. Additionally, auxiliary substances, such as wetting or emulsifying agents, pH buffering substances, gels or gelling materials, flavorings, colorants, microspheres, polymers, suspension agents, etc. may also be present herein. In addition, one or more other conventional pharmaceutical ingredients, such as preservatives, humectants, suspending agents, surfactants, antioxidants, anticaking agents, fillers, chelating agents, coating agents, chemical stabilizers, etc. may also be present, especially if the dosage form is a reconstitutable form. Suitable exemplary ingredients include macrocrystalline cellulose, carboxymethyf cellulose sodium, polysorbate 80, phenyletbyl alcohol, chiorobutanol, potassium sorbate, sorbic acid, sulfur dioxide, propyl gallate, the parabens, ethyl vanillin, glycerin, phenol, parachlorophenol, gelatin, albumin and a combination thereof. A thorough discussion of pharmaceutically acceptable excipients is available in REMINGTON'S PHARMACEUTICAL SCIENCES (Mack Pub. Co., N.J. 1991) which is incorporated by reference herein.

In some embodiments, the invention relates to the identification, production, and use of agents which modulate FMRP gene expression or the activity of the FMRP gene product including but not limited to nucleic acid encoding FMRP and homologues, analogues, and deletions thereof, as well as a chemical compound, a peptide or analog thereof, an antibody or an antigen-binding fragment of said antibody, antibody mimetic, or a nucleic acid; and pharmaceutical formulations and routes of administration for such compounds.

An assay employing FMRP transfectants can be used to successfully identify agents which modulate the expression of the FMRP gene. Assays for the activity of the FMRP gene product are also described.

The present invention also comprises antisense oligonucleotides specific for the FMRP transcript; antibodies (fragments and mimetics) to the gene product; cell lines engineered to stably express FMRP; assays for screening compounds, including peptides, polynucleotides, and small organic molecules, to identify those that inhibit the expression or activity of the FMRP gene product; and methods of treating diseases characterized by FMRP activity using such compounds.

Human FMRP protein would be useful for in vitro studies on the mechanism of action of the human FMRP and particularly for further studies on the mechanism of action of any inhibitors that are selective for FMRP that are identified by drug screening, or for investigating the mechanism of action of existing drugs or of inhibitors that may be identified by other means. The purified human FMRP protein would also be useful for the production of crystals suitable for X-ray crystallography. Such crystals would be extremely beneficial for the rational design of drugs based on molecular structure.

The present invention provides an in vitro system for the screening of agents that modulate FMRP stability and/or activity. Assays can be performed on living mammalian cells, which more closely approximate the effects of a particular serum level of agent in the body, or on microsomal extracts prepared from the cultured cell lines. Studies using microsomal extracts offer the possibility of a more rigorous determination of direct interactions.

Thus, the present invention also provides a method to evaluate the relative inhibitory activity of an agent to selectively inhibit FMRP. This assay comprises, for example, contacting a FMRP-expressing transgenic cell line or a microsomal extract thereof with a preselected amount of an agent in a suitable culture medium or buffer, adding arachidonic acid to the mixture, and measuring the level of synthesis of a FMRP or activity of FMRP protein, by said cell line, or said microsomal extract, as compared to a control cell line or portion of microsomal extract in the absence of said agent.

In some embodiments, the present invention provides a method of determining the ability of an agent to inhibit FMRP activity in cells comprising:

-   -   (1) adding a first preselected amount of said agent to a cell in         culture medium, which cell contains a DNA sequence which         expresses FMRP;     -   (2) measuring the level of a FMRP activity by said cell; and     -   (3) comparing said level with the level of FMRP activity by cell         line in the absence of said agent.

In some embodiments, the cell is a transgenic cell. In some embodiments, the cell is a transgenic cell line. In some embodiments, the transgenic cell or transgenic cell line comprises cells which contains a chromosomally integrated, recombinant DNA sequence, which expresses FMRP. In some embodiments, the cell is a mammalian cell. In some embodiments, the cell does not express autologous FMRP activity.

In some embodiments, the cell is a human or mouse cancer cell that has in the course of tumorigenesis and malignant progression markedly upregulated expression of FMRP so as to acquire resistance to immune attack.

In some embodiments, the FMRP is mammalian FMRP, preferably human FMPR.

In some embodiments, the level of expression of and/or activity of FMRP is determined by the agent disrupting the binding of by FMRP to its target RNA.

In some embodiments, the present invention provides a method of identifying an agent that modulates the expression and/or activity of i) the FMRP protein, ii) an mRNA encoding the FMRP and/or iii) the FMR1 gene, the method comprising:

-   -   (1) providing a sample expressing FMRP;     -   (2) contacting the biological sample with a test agent;     -   (3) determining the level of expression of and/or activity of         FMRP;     -   (4) comparing the level of expression and/or activity with a         control sample not contacted by the test agent; and     -   (5) selecting a test agent that decreases the level of         expression of and/or activity of FMRP.

In some embodiments, the sample is a cell that naturally expresses high levels of endogenous FMRP. In some embodiments, the sample is a cell that is engineered to express FMRP.

In some embodiments, the cell is a transgenic cell. In some embodiments, the cell is a transgenic cell line. In some embodiments, the transgenic cell or transgenic cell line comprises cells which contains a chromosomally integrated, recombinant DNA sequence, which expresses FMRP. In some embodiments, the cell is a mammalian cell. In some embodiments, the cell does not express autologous FMRP activity.

In some embodiments, the cell is a human or mouse cancer cell that has in the course of tumorigenesis and malignant progression markedly upregulated expression of FMRP so as to acquire resistance to immune attack.

In some embodiments, the FMRP is mammalian FMRP, preferably human FMPR.

In some embodiments, the level of expression of and/or activity of FMRP is determined by the agent disrupting the binding of by FMRP to its target RNA.

The agents identified in a screen will demonstrate the ability to selectively modulate the expression and/or activity of FMRP. These agents include but are not limited to nucleic acid encoding FMRP and homologues, analogues, and deletions thereof, as well as a chemical compound, a peptide or analog thereof, an antibody or an antigen-binding fragment of said antibody, antibody mimetic, or a nucleic acid.

The DNA of the invention encoding the FMRP gene or homologues, analogues, or fragments thereof may be used in accordance with the invention to diagnose disease states which are phenotypic of an FMRP genotype or of FMRP expression.

Alternatively, the pharmaceutical composition of the invention further comprises one of several components of an anti-cancer therapy. Preferably, the anti-cancer therapy comprises a therapeutically effective amount of an immune checkpoint inhibitor. Preferably, the immune checkpoint inhibitor is selected from the group comprising a PD-1 inhibitor, a PD-L1 inhibitor, and a CTLA-4 inhibitor, or a combination thereof. Alternatively, or additionally, the one or more anti-cancer therapy is a chemotherapeutic agent or cocktail of multiple different chemotherapeutic agents as described herein.

As used herein, a “PD-1 inhibitor” means any agent that interferes or blocks the binding of PD-1 receptor on T cells with its ligands, PD-L1 and PD-L2, which are present on tumor cells. The PD-1 inhibitor may be an antibody or a fragment thereof, which interferes with, inhibits, or blocks the PD-1 binding to its ligands. A PD-1 inhibitor may also be a small molecule or any other agent. Non-limiting examples of PD-1 inhibitor comprise nivolumab, pembrolizumab, pidilizumab, BMS 936559, MPDL3280A, MSB0010718C BGB-108 and mDX-400 and MEDI4736.

Non-limiting examples of PD-L1 inhibitors are selected from the group comprising MEDI-0680, RG-7446, durvalumab, KY-1003, KD-033, MSB-0010718C, TSR-042, ALN-PDL, STI-A1014 and BMS-936559.

As used herein, a “CTLA-4 inhibitor” means any agent that interferes or blocks CTLA-4 such as anti-CTLA-4 mAb or blocker, e.g., ipilimumab, tremelimumab and abatacept.

In another aspect, the anti-cancer therapy directed at FMRP is included in combination with a therapeutically effective amount of an anti-tumor-vaccine, including personalized neo-antigen cocktails, or other immune-stimulatory agents that bolster anti-tumor immune responses.

The present invention further provides a method of treatment and/or prevention of cancer and/or cancer metastasis in a subject in need thereof, comprising administering to said subject a pharmaceutical composition of the invention, alone or in combination with one or more anti-cancer therapy. Most preferably, the anti-cancer therapy comprises a therapeutically effective amount of an immune checkpoint inhibitor. Preferably, the immune checkpoint inhibitor is selected from the group comprising a PD-1 inhibitor, a PD-L1 inhibitor, and a CTLA-4 inhibitor, or a combination thereof. Alternatively, or additionally, the anti-cancer therapy is a chemotherapeutic agent or cocktail of multiple different chemotherapeutic agents as described herein.

It will be appreciated that the combination of a pharmaceutical composition of the invention and the PD-1/PD-L 1/CTLA-4 inhibitor may be administered in any order or concurrently. In selected aspects, the pharmaceutical composition and PD-1/PD-L 1/CTLA-4 will be administered to patients that have previously undergone treatment with other anti-cancer agents. In certain other aspects, the pharmaceutical composition and the PD-1/PD-L 1/CTLA-4 inhibitor will be administered substantially simultaneously or concurrently. For example, a subject may be given a pharmaceutical composition of the invention while undergoing a course of treatment with the PD-1/PD-L 1/CTLA-4 inhibitor. In addition, it is contemplated that the subject has already or may be concurrently receiving other forms of cancer therapy, e.g., chemotherapy. In certain aspects, the pharmaceutical composition of the invention will be administered within 1 year of the treatment with the PD-1/PD-L 1/CTLA-4 inhibitor. In certain alternative aspects, the pharmaceutical composition of the invention will be administered within 10, 8, 6, 4, or 2 months of any treatment with the PD-1/PD-L 1/CTLA-4 inhibitor and/or additional anti-cancer therapy. In certain other aspects, the pharmaceutical composition of the invention will be administered within 4, 3, 2, or 1 week of any treatment with the PD-1/PD-L 1/CTLA-4 inhibitor and/or additional anti-cancer agent or therapy. In some aspects, the pharmaceutical composition of the invention will be administered within 5, 4, 3, 2, or 1 days of any treatment with the PD-1/PD-L 1/CTLA-4 inhibitor and/or additional anti-cancer therapy or agent. It will further be appreciated that the pharmaceutical composition of the invention and the PD-1/PD-L 1/CTLA-4 inhibitor and/or additional anti-cancer agent or therapy may be administered to the subject within a matter of hours or minutes (i.e., substantially simultaneously).

In embodiments, the agent of the invention could be combined with other immunomodulator agents that either sustain the killing activity and abundance of T cell (and NK cells), or disrupt other barriers, such as myeloid derive suppressor cells (MDSC) and immuno-suppressive macrophages in so far as their activities are complementary to the effects of inhibiting FMRP.

In some embodiments, the agent of the invention could be combined an ADAR1 inhibitor. Knockout (i.e. genetic inhibition) of ADAR1, an immunosuppressive RNA editing enzyme, has combinatorial benefit in extending overall survival in double-KO tumors also carrying a knockout of FMRP.

Anticancer agents that may be administered in combination with the pharmaceutical composition of the invention and PD-1/PD-L 1/CTLA-4 inhibition include chemotherapeutic agents. Thus, in some aspects, the method or treatment involves the combined administration of a pharmaceutical composition of the invention and PD-1/PD-L 1/CTLA-4 inhibitor and a chemotherapeutic agent or cocktail of multiple different chemotherapeutic agents. Treatment with a pharmaceutical composition of the invention can occur prior to, concurrently with, or subsequent to administration of these other therapies. Chemotherapies contemplated by the invention include chemical substances or drugs which are known in the art and are commercially available, such as gemcitabine, irinotecan, doxorubicin, 5-fluorouracil, cytosine arabinoside (“Ara-C”), cyclophosphamide, thiotepa, busulfan, cytoxin, TAXOL, methotrexate, cisplatin, melphalan, vinblastine and carboplatin. Combined administration can include co-administration, either in a single pharmaceutical formulation or using separate formulations, or consecutive administration in either order but generally within a time period such that all active agents can exert their biological activities simultaneously. Preparation and dosing schedules for such chemotherapeutic agents can be used according to manufacturers' instructions or as determined empirically by the skilled practitioner.

Chemotherapeutic agents useful in the instant invention also include, but are not limited to, alkylating agents such as thiotepa and cyclosphosphamide (CYTOXAN); alkyl sulfonates such as busulfan, improsulfan, and piposulfan; aziridines such as benzodopa, carboquone, meturedopa, and uredopa; ethylenimines and methylamelamines including altretamine, triethylenemelamine, trietylenephosphoramide, triethylenethiophosphaoramide and trimethylolomelamime nitrogen mustards such as chlorambucil, chlornaphazine, cholophosphamide, estramustine, ifosfamide, mechlorethamine, mechlorethamine oxide hydrochloride, melphalan, novembichin, phenesterine, prednimustine, trofosfamide, uracil mustard; nitrosureas such as carmustine, chlorozotocin, fotemustine, lomustine, nimustine, ranimustine; antibiotics such as aclacinomysins, actinomycin, authramycin, azaserine, bleomycins, cactinomycin, calicheamicin, carabicin, caminomycin, carzinophilin, chromomycins, dactinomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine, doxorubicin, epirubicin, esorubicin, idarubicin, marcellomycin, mitomycins, mycophenolic acid, nogalamycin, olivomycins, peplomycin, potfiromycin, puromycin, quelamycin, rodorubicin, streptonigrin, streptozocin, tubercidin, ubenimex, zinostatin, zorubicin; anti-metabolites such as methotrexate and 5-fluorouracil (5-FU); folic acid analogues such as denopterin, methotrexate, pteropterin, trimetrexate; purine analogs such as fludarabine, 6-mercaptopurine, thiamiprine, thioguanine; pyrimidine analogs such as ancitabine, azacitidine, 6-azauridine, carmofur, cytarabine, dideoxyuridine, doxifluridine, enocitabine, floxuridine, 5-FU; androgens such as calusterone, dromostanolone propionate, epitiostanol, mepitiostane, testolactone; anti-adrenals such as aminoglutethimide, mitotane, trilostane; folic acid replenisher such as frolinic acid; aceglatone; aldophosphamide glycoside; aminolevulinic acid; amsacrine; bestrabucil; bisantrene; edatraxate; defofamine; demecolcine; diaziquone; elformithine; elliptinium acetate; etoglucid; gallium nitrate; hydroxyurea; lentinan; lonidamine; mitoguazone; mitoxantrone; mopidamol; nitracrine; pentostatin; phenamet; pirarubicin; podophyllinic acid; 2-ethylhydrazide; procarbazine; PSK; razoxane; sizofuran; spirogermanium; tenuazonic acid; triaziquone; 2,2′,2″-trichlorotriethylamine; urethan; vindesine; dacarbazine; mannomustine; mitobronitol; mitolactol; pipobroman; gacytosine; arabinoside (“Ara-C”); cyclophosphamide; thiotepa; taxoids, e.g. paclitaxel (TAXOL, Bristol-Myers Squibb Oncology, Princeton, N.J.) and doxetaxel (TAXOTERE, Rhone-Poulenc Rorer, Antony, France); chlorambucil; gemcitabine; 6-thioguanine; mercaptopurine; methotrexate; platinum analogs such as cisplatin and carboplatin; vinblastine; platinum; etoposide (VP-16); ifosfamide; mitomycin C; mitoxantrone; vincristine; vinorelbine; navelbine; novantrone; teniposide; daunomycin; aminopterin; xeloda; ibandronate; CPT11; topoisomerase inhibitor RFS 2000; difluoromethylornithine (OMFO); retinoic acid; esperamicins; capecitabine; and pharmaceutically acceptable salts, acids or derivatives of any of the above. Chemotherapeutic agents also include anti-hormonal agents that act to regulate or inhibit hormone action on tumors such as anti-estrogens including for example tamoxifen, raloxifene, aromatase inhibiting 4(5)-imidazoles, 4-hydroxytamoxifen, trioxifene, keoxifene, L Y117018, onapristone, and toremifene (Fareston); and antiandrogens such as flutamide, nilutamide, bicalutamide, leuprolide, and goserelin; and pharmaceutically acceptable salts, acids or derivatives of any of the above.

In certain aspects, the therapeutic agent is a kinase inhibitor. In certain aspects, the kinase inhibitor is a multi-targeted receptor tyrosine kinase inhibitor. Kinase inhibitors include, but are not limited to, sunitinib, pazopanib, crizotinib, dasatinib. In certain aspects, the second anticancer agent is sunitinib.

In certain aspects, the therapeutic agent is an inhibitor of mammalian target of rapamycin (mTOR). mTOR inhibitors include, but are not limited to, temsirolimus, sirolimus, deforolimus and everolimus. In certain aspects, the second anticancer agent is everolimus.

In certain aspects, therapeutic agent is a somatostatin analog. Somatostatin analogs act through interaction with specific, high affinity membrane receptors for somatostatin. Somatostatin analogs include, but are not limited to, octreotide, somatuline, and RC 160 (octastatin). In certain aspects, the second anticancer agent is octreotide.

In certain aspects, the chemotherapeutic agent is a topoisomerase inhibitor. Topoisomerase inhibitors are chemotherapy agents that interfere with the action of a topoisomerase enzyme (e.g., topoisomerase I or II). Topoisomerase inhibitors include, but are not limited to, doxorubicin HCl, daunorubicin citrate, mitoxantrone HCl, actinomycin 0, etoposide, Topotecan HCl, teniposide (VM-26), and irinotecan. In certain aspects, the second anticancer agent is irinotecan.

In certain aspects, the chemotherapeutic agent is an alkylating agent. In certain aspects, the chemotherapeutic agent is temozolomide.

In certain aspects, the chemotherapeutic agent is an anti-metabolite. An anti-metabolite is a chemical with a structure that is similar to a metabolite required for normal biochemical reactions, yet different enough to interfere with one or more normal functions of cells, such as cell division. Anti-metabolites include, but are not limited to, gemcitabine, fluorouracil, capecitabine, methotrexate sodium, ralitrexed, pemetrexed, tegafur, cytosine arabinoside, THIOGUANINE (GlaxoSmithKline), 5-azacytidine, 6-mercaptopurine, azathioprine, 6-thioguanine, pentostatin, fludarabine phosphate, and cladribine, as well as pharmaceutically acceptable salts, acids, or derivatives of any of these. In certain aspects, the second anticancer agent is gemcitabine. In certain aspects, the tumor to be treated is a pancreatic neuroendocrine tumor and the second anticancer agent is an anti-metabolite (e.g., gemcitabine).

In certain aspects, the chemotherapeutic agent is an antimitotic agent, including, but not limited to, agents that bind tubulin. By way of non-limiting example, the agent comprises a taxane. In certain aspects, the agent comprises paclitaxel or docetaxel, or a pharmaceutically acceptable salt, acid, or derivative of paclitaxel or docetaxel. In certain aspects, the agent is paclitaxel (TAXOL), docetaxel (TAXOTERE), albumin-bound paclitaxel (e.g., ABRAXANE), DHA-paclitaxel, or PG-paclitaxel. In certain alternative aspects, the antimitotic agent comprises a vinca alkaloid, such as vincristine, vinblastine, vinorelbine, or vindesine, or pharmaceutically acceptable salts, acids, or derivatives thereof. In some aspects, the antimitotic agent is an inhibitor of Eg5 kinesin or an inhibitor of a mitotic kinase such as Aurora A or Plk1.

In certain aspects, the treatment involves the combined administration of a pharmaceutical composition of the invention and a PD-1/PD-L 1/CTLA-4 inhibitor described herein and radiation therapy. Treatment with the pharmaceutical composition of the invention can occur prior to, concurrently with, or subsequent to administration of radiation therapy. Any dosing schedule for such radiation therapy can be used as determined by the skilled practitioner.

In other aspects of the invention, the pharmaceutical compositions of the invention is a sustained-release formulation, or a formulation that is administered using a sustained-release device. Such devices are well known in the art, and include, for example, transdermal patches, and miniature implantable pumps that can provide for drug delivery over time in a continuous, steady-state fashion at a variety of doses to achieve a sustained-release effect with a non-sustained-release pharmaceutical composition.

In other aspects of the invention, the pharmaceutical compositions of the invention is administered prior to, during and/or after said patient was subjected to a radiation therapy.

“Radiation therapy” refers to the use of high-energy radiation to shrink tumors and kill cancer cells. Examples of radiation therapy include, without limitation, external radiation therapy and internal radiation therapy (also called brachytherapy).

External radiation therapy is most common and typically involves directing a beam of direct or indirect ionizing radiation to a tumor or cancer site. While the beams of radiation, the photons, the Cobalt or the particule therapy are focused to the tumor or cancer site, it is nearly impossible to avoid exposure of normal, healthy tissue. Energy source for external radiation therapy is selected from the group comprising direct or indirect ionizing radiation (for example: x-rays, gamma rays and particle beams or combination thereof).

Internal radiation therapy involves implanting a radiation-emitting source, such as beads, wires, pellets, capsules, etc., inside the body, at, or near to the tumor site. Energy source for internal radiation therapy is selected from the group of radioactive isotopes comprising: iodine (iodine125 or iodine131), strontium89, radioisotopes of phosphorous, palladium, cesium, indium, phosphate, or cobalt, and combination thereof. Such implants can be removed following treatment, or left in the body inactive. Types of internal radiation therapy include, but are not limited to, interstitial, and intracavity brachytherapy (high dose rate, low dose rate, pulsed dose rate).

A currently less common form of internal radiation therapy involves biological carriers of radioisotopes, such as with radio-immunotherapy wherein tumor-specific antibodies bound to radioactive material are administered to a patient. The antibodies bind tumor antigens, thereby effectively administering a dose of radiation to the relevant tissue.

Methods of administering radiation therapy are well known to those of skill in the art.

The pharmaceutical compositions of the present invention may be administered to a subject by different routes including, but not limited to, orally, parenterally, sublingually, transdermally, rectally, transmucosally, topically, via inhalation, via buccal administration, intrapleurally, intravenous, intraarterial, intraperitoneal, subcutaneous, intramuscular, intranasal, intratumoral, intrathecal, and intraarticular or combinations thereof. For human use, the composition may be administered as a suitably acceptable formulation in accordance with normal human practice. The skilled artisan will readily determine the dosing regimen and route of administration that is most appropriate for a particular patient. The compositions of the invention may be administered by traditional syringes, needleless injection devices, “microprojectile bombardment gone guns”, or other physical methods such as electroporation (“EP”), “hydrodynamic method”, or ultrasound.

The pharmaceutical compositions of the present invention may also be delivered to the patient, by several technologies including DNA injection (also referred to as DNA vaccination) with and without in vivo electroporation, liposome mediated, nanoparticle facilitated, recombinant vectors such as recombinant lentivirus, recombinant adenovirus, and recombinant adenovirus associated virus sa described herein. The compositions may be injected intra veniously or locally injected in the brain or muscle or electroporated in the tissue of interest such as, e.g., muscle, brain, liver, prostate, breast, kidney(s), and hematopoietic system.

The agent and/or pharmaceutical compositions of the present invention may be used in any method where modulating the expression and/or the immuno-suppressive activity of i) the FMRP protein, ii) an mRNA encoding the FMRP protein, and/or iii) the FMR1 gene that encodes FMRP would be beneficial.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications without departing from the spirit or essential characteristics thereof. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations or any two or more of said steps or features. The present disclosure is therefore to be considered as in all aspects illustrated and not restrictive, the scope of the invention being indicated by the appended Claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein. Various references are cited throughout this Specification, each of which is incorporated herein by reference in its entirety. The foregoing description will be more fully understood with reference to the following Examples.

EXAMPLES Example 1 Material and Methods Generation of Crisper-Edited Tumor Cell Line

Mouse PDAC 4361.12 cells were cultured in DMEM with 10% FBS. The FMR1 gene was knocked out in cells using the CRISPR/Cas9 system. Cells were transiently transfected with two Cas9 and single-guide RNAs (sgRNA) expression plasmids and selected by blasticidin for five days. This transient CRISPR strategy for the knockout of FMRP prevents any potential unspecific effects mediated by stable integration of Cas9/sgRNA into the genome. The guide sequences used for FMR1 are 5′-GTGGAAGTGCGGGGCTCCAA-3′ (SEQ ID NO: 12) or 5′-GAGCTGGTGGTGGAAGTGCG-3′ (SEQ ID NO: 13). Cells were single-cell plated into 96-well plate without blasticidin. Knockout clones were selected by immunoblot blotting for the lack of FMRP proteins. Obtained FMRP KO cells kept sensitive to blasticidin, indicating the CRISPR/Cas9 system was only transiently expressed in those cells. Two independent KO clones and WT clones (transfected with a Cas9 abd an empty SgRNA vectors) were analyzed as indicated.

Animal Studies

All experiments using animals were performed in accordance with protocols approved by the local animal experimentation committee of the Canton de Vaud (license number 3214). FVBn, Balb/c or C57B/6, NSG or SCID/beige mice were used at 8 weeks of age. For the lung metastasis assay, 2X10{circumflex over ( )}5 mouse PDAC WT or FMRP KO cells suspended in 200 μl PBS were injected into were injected into the lateral tail vein of the mice. For the primary tumor growth assay, 5X10{circumflex over ( )}5 cells suspended in 100 μl PBS were injected subcutaneously into the mice.

Analysis of Tumor-Infiltrating Lymphocytes by Flow Cytometry

Flow cytometry was performed using a BD LSRII Fortessa and results were analyzed using FlowJo software (Treestar). Primary tumor cell suspensions were blocked by mouse Fc block (anti CD16/CD32; Biolegend, #101312) prior to staining. Fluorochrome conjugated anti-mouse CD45 (clone 30F-11), CD3e (clone 145-2C11), CD8a (clone 53-6.7), Granzyme B (clone NGZB), TNFa (MP6-XT22) and IFNg (clone XMG1.2) antibodies were used following the manufacturers protocol. Blue UV was used to stain dead cells. To analyze intracellular cytokine expression, mice bearing s.c. tumors were I.P. injected with 250 μg protein transport inhibitor Brefaldin A (BD biosciences, #555029) 6 hrs before the sacrifice. Intracellular cytokine staining was then performed using Fixation/Permeabilization Solution Kit (Sigma, B6542-25MG).

Immunohistochemical and Immunofluorescent Staining

Harvested mouse tissues were fixed in 4% paraformaldehyde overnight, embedded in paraffin, and sectioned by microtome (Leica). Antigen retrieval was performed in a citrate buffer (pH=6.0) in a water bath at 95° C. for 20 min, or in a tris-EDTA buffer (pH=8.0) in water bath at 95° C. for 10 min. Primary antibodies were incubated at 4° C. overnight. For Immunohistochemical (IHC) staining, 2nd antibodies (ImmPRESS HRP reagent kit, anti-rabbit MP-7401 and anti-rat MP-7444) were incubated at room temperature for 45 min, and finally visualized with the peroxidase substrate DAB (Sigma-Aldrich, D5637-1G) for the same amount of time (maximum 10 min) at room temperature. The stained tissue sections were counterstained with Meyer's hematoxylin. For Immunofluorescent (IF) staining, 2nd antibodies (Alexa Fluor 488, 568, 647, Thermo Fisher Scientific) were incubated at room temperature for 45 min. Images were acquired with Leica DM5500B and Zeiss LSM 700 upright confocal microscopes, and analyzed with Image J. Antibodies used are as follows, FMRP, Abcam, ab191411; mouse CD8, Thermo Fisher Scientific, 14-0808-82.

Statistical Analysis

Statistical analysis was performed with Prism 7 (GraphPad Software). Unless stated otherwise, the Student's t test was used for non-paired experiments (two-tailed). Wilcoxon matched pairs test (two-tailed) was performed for paired experiments that did not follow a Gaussian distribution. P<0.05 was considered statistically significant. Values are mean f SEM.

Results

A recent study revealed that FMRP acts as a downstream effector of NMDAR signaling in promoting the invasive growth of pancreatic cancer.¹⁶ We further confirmed the elevated FMRP expression is found in human (data not shown) and murine PDAC tissues (FIG. 1A).

To further explore the role of FMRP in tumor progression, we used the Crisper/Cas9 system¹⁰ to knock-out FMRP in murine pancreatic adenocarcinoma (PDAC) cell line 4361.12 (FIG. 1B), which is a single cell-derived cell line from the P48-cre; LSL-Kras^(G12D); P53^(R172H/+) PDAC mouse model in the FvBn background. Importantly, a transient Crisper strategy for the knock-out of FMRP was performed to avoid any potential unspecific effects and immunogenicity mediated the stable Cas9/sgRNA genome integration.

In vitro functional assay shows that there are no significant differences in colony formation capabilities between WT and FMRP KO PDAC cells (FIG. 1C). Considering the possible role of FMRP in metastasis, we first injected WT and FMRP KO cells into the tail vein of the immunocompetent FVBn mice, a standard in vivo lung metastasis assay (FIG. 1D). Strikingly, two out of the five mice injected with the FMRP-KO2 cells survived for 120 days after the injection, while all the five mice injected with the FMRP-WT cells died before 25 days after the injection (FIG. 1E). When a similar in vivo lung metastasis assay was performed in immunodeficient SCID/beige mice, there was not such a profound difference in overall survival between these two groups (FIG. 1F), implicating the adaptive immune system in the survival benefit observed in mice bearling FMRP-KO tumors. We then turned to use a primary tumor model formed by subcutaneous injection of cancer cells (FIG. 1H). Tumor growth of FMRP-KO cells was seriously impaired compared with FMRP-WT cells when they were subcutaneously injected into FVBn mice, while no significant change in tumor weight between these two groups was observed when the cells were subcutaneously injected into immunodeficient NSG mice (FIGS. 1I and 1J), further implicating a possible role of FMRP in modulating anti-tumor immunity in vivo.

Importantly, IHC staining of tumors formed from WT and FMRP-KO cancer cells revealed a large number of infiltrated CD8+ cytotoxic T cells in the KO tumors; in sharp contrast, there were almost no CD8+ T cells in WT tumors (FIG. 2A). FMRP KO tumors also have increased numbers of CD45+ immune cells compared with WT tumors (FIG. 2B). Consistently, FACS analysis of primary cell suspensions from WT and FMRP-KO tumors further demonstrated the dramatically increased number of CD45+ immune cells, CD3+CD8+ T cells, and GRZb+, IFNγ+ and TNF+ T cells in KO tumors compared with WT tumors (FIG. 2C-2G), further supporting the role of FMRP in suppressing anti-tumor immunity in vivo. Double IHC staining of FMRP and CD8 in mouse PDAC tissues was further performed, and found that CD8 T cells were be barely detectable in the center of FMRP-expressing tumors (FIG. 2H). Significant reverse association between FMRP expression and CD8 T cell infiltration in human PDAC samples was also determined.

Whether the deletion of FMRP in cancer cells changed the expression of immune checkpoint proteins so as to trigger the anti-tumor immune responses was explored. If FMRP-suppressed anti-tumor immunity depended on the well-established T cell co-inhibitory PD-1 or CTLA-4 signaling, downregulation in FMRP-KO tumor cells of PD-1 ligands PD-L1/CD274 and PD-L2/PDCDILG2, or perhaps the CTLA-4 ligands B7/B7-1/CD80 and CD86 would be expected. However, WB analysis and IHC staining shows unchanged PD-L1 expression comparing WT and FMRP KO cells in vitro and in vivo (FIG. 3A-B), while PDL2, CD86, and CD80 were barely detected in either (data not shown), indicating that the underlying mechanism of FMRP-mediated immune resistance in this PDAC cancer cell line does not involve suppression of PD-1 or CTLA-4 immune checkpoint ligands.

Additionally, we also performed a pre-clinical trial using anti-PD1 antibody on the WT tumors formed in immunocompetent FVBn mice, which revealed that WT PDAC tumors are non-responsive to anti-PD-1 therapy, recaptulating the unresponsiveness to anti-PD1 therapy in human PDAC patients (FIG. 3C). Despite this therapeutic resistance to anti-PD1 checkpoint immunotherapy, the derivative PDAC tumor cells with a KO of FMRP have strikingly impaires tumor growth in vivo (FIG. 1 ), which is associated with an influx of CD8 T cells (FIG. 2 ). The results suggest that FMRP inhibitors could be used as a novel immunotherapy strategy in the treatment of PDAC and other tumors that fail to respond to checkpoint inhibitors. Intringingly, PD1 antibody treatment in FMRP KO tumors further suppresses the tumor growth, indicating that the combination of anti-PD1 antibody with the FMRP knockout has combinatorial benefit in extending survival (FIG. 3D).

As a recent study shows ADAR1, an RNA-binding protein that mediates A-to-I RNA super-editing, promotes resistance to immune checkpoint blockade.²³ Interestingly, another study shows that FMRP also regulates RNA surper-deiting in neurons by physically interacting with ADAR1. Strong interaction between FMRP and ADAR1 in mouse PDAC cells was confirmed by co-Immunoprecipitation (co-IP) and reverse co-IP (FIG. 4A-B). To determine whether the combination of FMRP and ADAR1 double KO would triggers much stronger anti-tumoral immune responses, ADAR1 single KO, and FMRP/ADAR1 double KO PDAC cells were generated using transient transfection of Cas9/sgRNA vectors targeting FMR1 and ADAR1 gene (FIG. 4C), and were injected into the sygenenic mice. Intringingly, the combination of the FMRP and ADAR1 KO signifantly prolonged overall survival compared with the FMRP single KO and ADAR1 single KO groups (FIG. 4D), supporting the clinical application of the combination of targeting FMRP and ADAR1 in cancer immunotherapy.

To more broadly explore the potential role of FMRP in suppression of anti-tumoral immunity in other types of cancer, dramatically increased FMRP expression in mouse colon tissue (FIG. 5A), melonoma tissues (FIG. 6A), pancreatic neuronendoccrine tumors (PNET) and liver metastasis (FIG. 7A), breast cancer tissues (FIG. 8A) compared with corresponding normal tissues was detected. Human data are consitent with the mouse data (not shown). Similarily, the FMRP KO in mouse colon cancer cells (FIG. 6B) and melanoma cells (FIG. 7B) does not significanlty impair colony formation—reflecting proliferative and survival capabilitiues—in vitro. However, the FMRP KO severely impaired colon tumor growth in sygenic mice, but not in immunodeficient mice (FIG. 6D-I, FIG. 7D-E). Increased number of CD8 T cells were only found in FMRP KO colon tumors but not in WT tumors (FIG. 6G). FMRP was also knocked-out in PanNET tumors developing in the RIP1-Tag2 (RT2) PanNET mouse model by crossing RIP-7 cre mice with RT2 mice and FMR1-floxed mice. Importantly, FMRP KO RT2 mice have a significantly prolonged survial compared with WT RT2 mice, strongly suporting a role of FMRP in promoting PNET tumor progression.

Additional surveys of FMRP expression in human tumors revealed significant upragulation in 30-100% of patients with a broad spectrum of cancer types, including all of the major forms of lethal solid tumors (see e.g., FIG. 11 ).

Example 2

Direct targeting of the RNA binding sites in FMRP using oligonucleotides and peptides to disrupt interactions implicated in FMRP's effector function.

The RGG and KH2 RNA binding domains of FMRP have been implicated in its functional activities in multiple studies (e.g., Vasilyev, 2015; Darnell 2005), and disrupting FMRA-RNA interactions by delivery of an abundance of competitive molecules based on structural knowledge about these interactions. In one variation of the method, DNA or RNA oligonucleotides representing the core sequences from sc1/kc RNAs that bind to RGG/KH2 domains, respectively, would be synthesized. In some embodiments, locked nucleic acid (LNA) technology could be included in the synthesis, aiming to increase both half-life of the oligonucleotides and their binding affinity. In a second variation, polypeptides spanning the RGG and KH2 domains of FMRP would be synthesized and tested. In some embodiments, the polypeptides are combined by a polypeptide linker. In both variations, the candidates would be tested first by delivery into cultured cancer cells that express FMRP, scoring for impaired invasiveness in a Boyden chamber assay as previously described (Li & Hanahan 2013; Li, Zeng, et al 2018) and illustrated in FIG. 9 . Candidate compounds would be inoculated into tumors composed on cancer cells expressing FMRP, such as those described in this application, assessing consequent infiltration of CD8 T cells, which are otherwise excluded by expression of FMRP. Variations on the method would employ transfection enhancers to increase uptake in tumors of the candidate oligonucleotides.

Example 3

Therapeutic suppression of FMRP by siRNAs

An increasingly well validated therapeutic strategy involves the delivery of siRNAs that bind to and destabilize or block translation of mRNAs into tissue of, so as to suppress production of proteins implicated in disease (Selvam 2017). In this method, siRNAs are designed to bind to and disrupt FMR1 mRNA (encoding FMRP) and assayed by delivery into FMRP tumors devoid of CD8 T cells. scoring for infiltration of such cells, using the gene knockout tumors described elsewhere in this application as a benchmark. Prior to such in vivo testing, candidate siRNAs (i.e., siCtrl: UAAGG CUAUG AAGAG AUAC (SEQ ID NO: 9; siFMRP #1: AUAAG AGACA ACUUG GUGC (SEQ ID NO: 10); and siFMRP #2: UAACUUCGGAAUUAUGUAG (SEQ ID NO: 11)) were tested in the cancer cell invasion assay, where the inhibitory capability of a prototypical siRNA to FMR1 mRNA are illustrated in FIG. 9 . In some embodiments, siRNAs to FMR1 could include additional refinements by, for example, chemical modifications to enhance stability and activity (Hassler 2018) and/or the use of ‘transfection’ reagents for enhancing the delivery of nucleic acids into cancer cells in tumors.

Example 4

Illustration of a High Throughput Biochemical Screening Method for Identifying Small Molecules that Bind to a Key Interaction Site on FMRP.

One well-described mode of interaction of FMRP involves its regulation of a select set of mRNAs that contain a G-quadruplex motif that binds to a domain called RGG on the FMRP protein. Binding of the G-quadruplex motif result is alterations in translation of the targeted mRNA. An RNA called sc1 binds tightly to the RGD domain of FMRP and is widely used as a prototype for FMRP's binding to target mRNAs. As such, compounds that disrupt the binding of sc1 RNA to FMRP could represent a) inhibitors of translational control mechanisms involving FMRP binding to mRNAs, and b) tight binders to the RGG site that do not necessarily inhibit all FMRP functions, in the case that other mechanisms of action of FMRP beyond the RGG domain are involved in its newly discovered immuno-suppressive activity.

A second mode of FMRP interaction involves its binding to high affinity RNA targets through its KH2 RNA binding domain (Darnell et al., 2005). Studies have identified a series of RNAs that had structural and sequence-specific features termed “kissing complex (kc) RNAs. For example, kc2 RNA is able to compete FMRP off of polyribosomes at half maximal concentration of ˜100 nM. Human and mouse studies have shown that single missense mutations in KH2 abrogate FMRP polysome association and cause severe forms of the Fragile-X syndrome. Compounds that disrupt binding of kcRNA to FMRP could disrupt FMRP polysome association and abrogate function. Such compounds could be an agent as disclosed herein. In some embodiments, the agent is a synthetic nucleic acid that disrupts binding of kcRNA to FMRP. In some embodiments, a synthetic nucleic acid could be used as benchmarks to screen for and identify other kinds of small molecule inhibitors that act to disrupt FMRP function.

Any suitable assay known in the art to identify inhibitors of RNA-binding proteins can be used to screen compound libraries for small molecules that interfered with binding of FMRP to its distinctive target mRNAs (see e.g., Roos et al 2016). The readout involved identification of compounds that, upon binding, release fluorescent quenching of a fluorophore covalently attached to the protein, whose emission is otherwise blocked by the bound target RNA molecule that is modified to carry a fluorescence quencher. As applied to FMRP, the method would be performed as follows, and schematically illustrated in FIG. 10 .

For example, 1) human FMRP protein is produced in human HEK 293 cells, purified, and biochemically labeled with the fluorescent reporter fluorescein. 2) The sc1 RNA would be labeled with a fluorescence quencher molecule, for example Cy3 or BHQ, such that when sc1 is bound to FMRP, the excitable fluorescence emission of FITC is quenched. 3) FITC-FMRP and sc1-Cy3/BCG would be combined and aliquoted into 384 well microwells, after which chemical compounds from large compound libraries would be added to each well. The assay would best be performed in an HTP screen facility, where robots would prepare the micro-wells containing the protein/RNA complex, add coded compounds to each well, and then read out fluorescence emissions. 4) Compounds that elicited the release of the quenched fluorescence would be subjected to further characterization to validate their capability to disrupt the interaction of FMRP and sc1. 5) Such ‘leads’ would then be further characterized, to reveal binding affinity and kinetic parameters using microscale thermophoresis (MST) measurements and biolayer Interferometry (BLI by ForteBio-Octet). The newly identified compounds will be further characterized by biochemical, structural and cell-based assays, and in tumor models, to ascertain whether the compounds inhibit FMRP's functions and/or binds tightly to FMRP protein irrespective of functional inhibition. Tight binders could become components of protein degradation molecules designed to selectively degrade FMRP protein, irrespective of whether the compound proved to be a functional inhibitor itself.

Example 5

Identifying Compounds that Inhibit Expression of FMRP/FMR1.

Cancer cells expressing high levels of endogenous FMRP protein and mRNA would be engineered with an FMRP promoter driving GFP, along with a ubiquitous promoter driving RFP. Cell based HTP screens would be performed, scoring for compounds that suppress green fluorescence (FMRP transcription) but not red fluorescence (cell viability). Initial hits would be filtered by immuno-staining for endogenously expressed FMRP since bona fide inhibitors of FMR1 transcription should suppress not only the reporter gene but FMR1 itself. A variation would be to engineer the cell line with a FMRP Promoter driving a fusion gene composed of FMRP and GFP, which could also score for translational and protein stability inhibitors. Methodology for HTP cell-based screens to identify transcriptional inhibitors are increasing being successfully applied (see e.g., Zhang, 2018; Vuong, 2016).

Applicants are filing a Sequence Listing via the Electronic Filing System as a text file. The contents of this file add no new matter.

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1-20. (canceled)
 21. A method of identifying an agent that modulates the expression and/or activity of i) the FMRP protein activity, ii) an mRNA encoding FMRP and/or iii) the FMR1 gene, the method comprising: (1) providing a sample expressing FMRP; (2) contacting the biological sample with a test agent; (3) determining the level of expression of and/or activity of FMRP; (4) comparing the level of expression and/or activity with a control sample not contacted by the test agent; and (5) selecting a test agent that decreases the level of expression of and/or activity of FMRP.
 22. The method according to claim 21, wherein the level of expression of and/or activity of FMRP is determined by the agent disrupting the binding of by FMRP to its target mRNAs, miRNAs, or proteins.
 23. The method according to claim 21, wherein said agent inhibits the translation of an RNA encoding FMRP.
 24. The method according to claim 21, wherein the agent inhibits the transcription of the FMR1 gene encoding FMRP.
 25. The method according to claim 21, wherein the agent inhibits or impairs the binding of the FMRP to a target mRNA or miRNA.
 26. An agent identified by the method according to claim
 21. 27. The agent according to claim 26, wherein the agent is a chemical compound, a peptide or analog thereof, an antibody or an antigen-binding fragment of said antibody, antibody mimetic, or a nucleic acid.
 28. The agent according to claim 27, wherein the agent is a nucleic acid is selected from the group comprising an nucleic acid encoding an miRNA, an siRNA, a piRNA, an hnRNA, an snRNA, an sg RNA, CRISPR-based loss-of-function system, an esiRNA, an shRNA, and an antisense oligonucleotide, a peptide or analog thereof, an antibody or an antigen-binding fragment of said antibody, an antibody mimetic, or a combination thereof.
 29. A plasmid or a vector comprising one or more nucleic acid(s) according to claim
 28. 30. A host cell comprising a plasmid or vector according to claim
 29. 31. A host cell comprising one or more nucleic acid(s) according to claim
 28. 32. The agent according to claim 27, wherein the agent is a chemical compound.
 33. A pharmaceutical composition comprising: i) a therapeutically effective amount of an agent according to claim 26, or ii) a plasmid or a vector of claim 29, or iii) a host cell of claim 30 or 31, and a pharmaceutically acceptable carrier or diluent.
 34. A method for the treatment of cancer and/or the treatment and/or prevention of a cancer metastasis in a subject in need thereof, the method comprising administering to the subject the pharmaceutical composition according to claim
 33. 35. The method according to claim 34, further comprising administering one or more anti-cancer therapy.
 36. The method according to claim 35, wherein the one or more anti-cancer therapy comprises a therapeutically effective amount of an immune checkpoint inhibitor.
 37. The method according to claim 35, wherein the immune checkpoint inhibitor is selected from the group comprising a PD-1 inhibitor, a PD-L1 inhibitor, and a CTLA-4 inhibitor, or a combination thereof.
 38. The method according to claim 35, wherein the one or more anti-cancer therapy is included in combination with a therapeutically effective amount of an anti-tumor-vaccine, including personalized neo-antigen cocktails, or other immune-stimulatory agents that bolster anti-tumor immune responses. 